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Abstract:

A system and method for supporting a workpiece includes a plurality of
support assemblies with movable heads. Positional errors are ascertained
for the heads based on different positions thereof and used to properly
position the heads to support the workpiece. Other inventive aspects are
directed to features of the support assemblies and heads thereof.

Claims:

1. A holding assembly comprising a plurality of support assemblies, each
support assembly comprising a head adapted to support a workpiece,
wherein each head includes a guided member having a contact surface
configured to contact the workpiece and a guide assembly configured to
guide the guided member about an axis that coincides with the contact
surface.

2. The holding assembly of claim 1 wherein each support assembly includes
a support rod arranged to maintain the corresponding head in a selected
position.

3. The holding assembly of claim 2 wherein the support rods of at least
some of the support assemblies are fixedly coupled to each respective
head to move therewith.

4. The holding assembly of claim 3 wherein each support assembly includes
complementary engaging surfaces configured to rotate the support rod to a
selected position as the engaging surfaces slide relative to each other.

5. The holding assembly of claim 4 wherein the engaging surfaces comprise
a first engaging surface fixedly attached to the support rod to move
therewith and a second engaging surface held in a stationary position.

6. The holding assembly of claim 5 wherein the first engaging surface is
formed on a collar encircling the support rod.

7. The holding assembly of claim 2 wherein each support assembly includes
a coupling assembly, wherein the coupling assembly includes a sliding
member slidable on the support rod and selectively fixed to the support
rod.

8. The holding assembly of claim 7 wherein at least one of the coupling
assemblies is configured to move the head in at least two dimensions
relative to the corresponding support rod.

9. The holding assembly of claim 8 wherein said at least one the coupling
assemblies includes a link pivotally connecting the head to the sliding
member.

10. The holding assembly of claim 9 wherein said at least one the coupling
assemblies includes a second sliding member slidable on the support rod
and selectively fixed to the support rod and a second link, the head
being pivotally connected to the second sliding member with the second
link.

11. The holding assembly of claim 2 wherein each support assembly includes
a sliding member slidable on the support rod and selectively fixed to the
support rod.

12. The holding assembly of claim 11 wherein the sliding member comprises
a brake having an expandable body encircling the support rod and
selectively expanded to provide a force to secure the brake and support
rod relative to each other.

13. The holding assembly of claim 12 wherein the brake comprises a
gripping sleeve encircling the support rod, the expandable body
encircling the gripping sleeve.

14. The holding assembly of claim 13 the brake comprises a first support
block engaging a first end of the gripping sleeve and a second support
block engaging a second end of the gripping sleeve.

15. A holding assembly comprising a plurality of support assemblies, each
support assembly comprising a head adapted to support a workpiece, a
support rod fixedly coupled to the head to move therewith, and
complementary engaging surfaces configured to rotate the support rod to a
selected position as the engaging surfaces slide relative to each other.

16. The holding assembly of claim 15 wherein the engaging surfaces
comprise a first engaging surface fixedly attached to the support rod to
move therewith and a second engaging surface held in a stationary
position.

17. The holding assembly of claim 16 wherein the first engaging surface is
formed on a collar encircling the support rod.

18. A holding assembly comprising a plurality of support assemblies, each
support assembly comprising a head adapted to support a workpiece, a
support rod arranged to maintain the corresponding head in a selected
position, a brake slidable on the support rod and selectively fixed to
the support rod, the brake having an expandable body encircling the
support rod and selectively expanded to provide a force to secure the
brake and support rod relative to each other.

19. The holding assembly of claim 18 wherein the brake comprises a
gripping sleeve encircling the support rod, the expandable body
encircling the gripping sleeve.

20. The holding assembly of claim 19 the brake comprises a first support
block engaging a first end of the gripping sleeve and a second support
block engaging a second end of the gripping sleeve.

[0002]The discussion below is merely provided for general background
information and is not intended to be used as an aid in determining the
scope of the claimed subject matter.

[0003]Holding fixtures for three dimensional workpieces are available from
Modig Machine AB of Virserum, Sweden and CNA Manufacturing Systems, Inc.
of Woodinville, Wash. These fixtures hold workpieces in a fixed position
through an array of posts. Each of the posts are equipped with a flexible
vacuum cup that when seated upon a portion of the surface of the
workpiece forms a vacuum. When a vacuum is pulled in each of the posts,
the workpiece is held securely. The posts are arranged in a grid pattern,
oriented vertically, such that when the vacuum cups are in a home or
resting position each of the vacuum cups lay in a common plane. In order
to hold a three dimensional part, each of the posts are adjusted
vertically so as to conform the posts taken as a whole to the outer
surface of the workpiece to be held. In the Modig System, a large setting
machine is provided to adjust the posts. In particular, a gantry setting
machine includes two guide rails positioned along opposite sides of the
grid of posts and a bridge spanning between the guide rails carries a
plurality of setting fixtures used to set the vertical height of each of
the posts. As indicated above, the posts are arranged in a grid pattern
of equally spaced rows and columns. The setting device, disposed on the
bridge, conforms to the row spacing of the posts in the grid. As the
bridge moves along the guide rails, the height of each of the setting
devices on the bridge is adjusted such that when the corresponding post,
located below each setting device, is actuated the post extends upwardly
until the desired height of the vacuum cup is obtained. The bridge is
moved along the grid on a column-by-column basis setting each column of
posts of the grid in this manner. The grid pattern of the posts and the
setting bridge may limit the extent of curvature that the workpieces can
have.

[0004]Another known fixture described in U.S. Pat. No. 7,444,742. The
fixture includes a plurality of support assemblies. Each support assembly
includes a linear actuator with an end adapted to support a workpiece, or
a portion thereof. Each end includes a moveable coupling adapted to hold
the workpiece engaging end in a selected orientation. A positioning
device is moveable to a position proximate each end of each support
assembly, for example, by a robotic arm or other positioning assembly. An
end of the positioning device is configured to operate each movable
coupling so as to obtain the selected orientation of each end of each
support assembly.

SUMMARY

[0005]This Summary and the Abstract herein are provided to introduce a
selection of concepts in a simplified form that are further described
below in the Detailed Description. This Summary and the Abstract are not
intended to identify key features or essential features of the claimed
subject matter, nor are they intended to be used as an aid in determining
the scope of the claimed subject matter. The claimed subject matter is
not limited to implementations that solve any or all disadvantages noted
in the background.

[0006]In one embodiment, a holding assembly includes a plurality of
support assemblies. Each support assembly has a head adapted to support a
workpiece, where each head includes a guided member having a contact
surface configured to contact the workpiece and a guide assembly
configured to guide the guided member about an axis that coincides with
the contact surface.

[0007]In another embodiment, each support assembly includes a support rod
arranged to maintain the corresponding head in a selected position. The
support rods of at least some of the support assemblies can be fixedly
coupled to each respective head to move therewith.

[0008]If desired, each support assembly can include complementary engaging
surfaces configured to rotate the support rod to a selected position as
the engaging surfaces slide relative to each other. In one embodiment,
the engaging surfaces include a first engaging surface fixedly attached
to the support rod to move therewith and a second engaging surface held
in a stationary position. For example, the first engaging surface can be
formed on a collar encircling the support rod.

[0009]In another embodiment, each support assembly includes a coupling
assembly having a sliding member slidable on the support rod and
selectively fixed to the support rod. If desired, at least one of the
coupling assemblies can include a link pivotally connecting the head to
the sliding member. In yet another embodiment, the at least one of the
coupling assemblies can include a second sliding member slidable on the
support rod and selectively fixed to the support rod, where the head is
pivotally connected to the second sliding member with the second link.

[0010]In yet another embodiment, the sliding member can comprise a brake
having an expandable body encircling the support rod and selectively
expanded to provide a force to secure the brake and support rod relative
to each other. The brake can include a gripping sleeve encircling the
support rod, where the expandable body encircles the gripping sleeve.
First and second support blocks can engage opposite ends of the gripping
sleeve.

[0011]In another embodiment a holding assembly includes a plurality of
support assemblies, where each support assembly has a head adapted to
support a workpiece, a support rod fixedly coupled to the head to move
therewith, and complementary engaging surfaces configured to rotate the
support rod to a selected position as the engaging surfaces slide
relative to each other. If desired, the engaging surfaces can comprise a
first engaging surface fixedly attached to the support rod to move
therewith and a second engaging surface held in a stationary position.
For example, the first engaging surface can be formed on a collar
encircling the support rod.

[0012]In yet another embodiment, a holding assembly includes a plurality
of support assemblies, where each support assembly has a head adapted to
support a workpiece, a support rod arranged to maintain the corresponding
head in a selected position, and a brake slidable on the support rod and
selectively fixed to the support rod. The brake has an expandable body
encircling the support rod that can be selectively expanded to provide a
force to secure the brake and support rod relative to each other. If
desired, the brake can include a gripping sleeve encircling the support
rod, where the expandable body encircles the gripping sleeve. First and
second support blocks can engage opposite ends of the gripping sleeve.

[0013]Another embodiment is a system for supporting a workpiece. The
system includes a holding assembly comprising a plurality of support
assemblies, each support assembly comprising a head adapted to support a
portion of the workpiece, each head being movable from a reference
position to a position remote from the reference position. A controller
is provided and configured to access a model of the holding assembly
having at least some of the support assemblies and a model of the
workpiece to be supported by the holding assembly, wherein the controller
is configured ascertain a position of each head of each of said at least
some of the support assemblies based on the model of the holding assembly
and the model of the workpiece to be supported, the controller configured
to provide output signals related to desired positions of the head.

[0014]In yet another embodiment, a method for configuring a holding
assembly comprising a plurality of support assemblies to support a
workpiece is provided, where each support assembly comprising a head
adapted to support a portion of the workpiece. The method includes
ascertaining the position of each head with a controller based on a
virtual model of the holding assembly and a virtual model of the
workpiece to be supported; and adjusting the position of each head based
on the corresponding ascertained position.

[0015]In yet another embodiment, a system for supporting a workpiece is
provided. The system includes a holding assembly having a plurality of
support assemblies. Each support assembly includes a head adapted to
support a portion of the workpiece and where each head is movable from a
reference position to a position remote from the reference position. A
controller is configured to ascertain a positional error associated with
each support assembly, the positional error being ascertained from the
reference position and the position remote from the reference position.
The controller is further configured to use the positional error to
adjust a position of each respective head in order to support the portion
of the workpiece.

[0016]In yet another embodiment, a method is provided for configuring a
holding assembly comprising a plurality of support assemblies to support
a workpiece, each support assembly comprising a head adapted to support a
portion of the workpiece. The method includes obtaining a reference
position for each head; obtaining a position remote from the reference
position for each head; ascertaining a positional error associated with
each support assembly with a controller, the positional error being
ascertained from the reference position and the position remote from the
reference position; and using the corresponding positional error to
adjust a position of each head in order to support the portion of the
workpiece.

[0017]The foregoing system and method can have one or more of the
following features. Each support assembly can include a support rod
arranged to provide support for each corresponding head. The heads can be
configured to tilt with respect to a longitudinal axis of each respective
support rod, and where the controller is configured to use the positional
error to adjust a tilt of the respective head with respect to the
longitudinal axis of the corresponding support rod. The heads can be
configured to rotate with respect to a longitudinal axis of the
corresponding support rod, and wherein the controller is configured to
use the positional error to adjust the rotation of each head with respect
to the longitudinal axis of the corresponding support rod.

[0018]The controller can be configured to access a model of the holding
assembly having at least some of the support assemblies and a model of
the workpiece to be supported by the holding assembly, where the
controller is further configured ascertain a position of each head of
each of said at least some of the support assemblies based on the model
of the holding assembly and the model of the workpiece to be supported.
The controller can be configured to ascertain a vector that is normal to
an outer surface of the workpiece for each support assembly based on the
corresponding positional error. The controller can be configured to use a
positioning system to ascertain the reference position and the position
remote from the reference position for each corresponding support
assembly.

[0019]A positioning system can be included and adapted to engage each of
the support assemblies to move each corresponding head. The positioning
system is coupled to the controller to receive command signals from
controller to selectively move each head of each support assembly in
multiple degrees of freedom depending on that provided by the support
assembly. It should be noted that at least with respect to the
embodiments described above that use a virtual model of the holding
assembly and the workpiece to ascertain the positions of the heads, the
form of support assemblies need not be limited to that shown and
described herein. For instance, the support assemblies can have one or
more actuators to move the support assembly in one or more degrees of
freedom. The positioning assembly can also have an aligning fixture to
engage the support assembly, where the aligning fixture can take a number
of forms. For instance, by way of example, the support assemblies and
aligning fixture described in U.S. Pat. No. 7,444,742 (which is hereby
incorporated by reference in its entirety) can be used.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a side elevational view of a flexible fixture.

[0021]FIG. 2 is a front elevational view of the flexible fixture.

[0022]FIG. 3 is a perspective view of a first embodiment of a support
assembly.

[0033]FIG. 14 is a flow chart for registration of support assemblies on a
holding assembly.

[0034]FIG. 15 is a flow chart for support assembly programming.

[0035]FIG. 16 is a flow chart for adjusting support assemblies.

[0036]FIG. 17 is a flow chart for loading a part or workpiece on the
holding assembly.

[0037]FIG. 18 is a side elevational view of second holding assembly.

[0038]FIG. 19 is a front elevational view of the second holding assembly.

[0039]FIG. 20 is a graphical illustration of positional errors.

[0040]FIG. 21 is a schematic illustration of a computing environment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0041]Referring to FIGS. 1-2, a gantry or positioning system is
illustrated at 11. The gantry system 11 includes a pair of space-apart
rails 13. In the exemplary embodiment, rails 13 are elevated, being
supported by supports 16. A bridge 10 spans between rails 13. Two trucks
14 are coupled to bridge 10 and coupled to rails 13 in order to provide
horizontal movement of bridge 10 in a direction parallel to the guide
rails 13. Bridge 10 supports at least one mast 12A and 12B. In the
embodiment illustrated, mast 12A is adapted to hold an end effector such
as a laser for performing work on a workpiece supported by a holding
assembly 17. If desired, mast 12B is also adapted to hold an end
effector, which can include for example, a drill for performing work on
the workpiece, but as further explained below, can also hold an aligning
fixture 18 (FIGS. 11-13), described below, used to position and/or orient
each of a plurality of support assemblies 19 comprising the holding
assembly 17. The support assemblies 19 can be mounted at different
heights as illustrated in FIGS. 1 and 2 or on a holding assembly that
comprises a flat support structure (FIGS. 18 and 19). In a further
embodiment, each support assembly 19 can be mounted at one of a plurality
of selected locations on the support structure/holding assembly 17.

[0042]In the embodiment illustrated, mast 12B comprises a telescoping
assembly in order to allow an end effector 21 attached to an end thereof
to move in a vertical direction wherein movement of the mast 12B along
the bridge 10 and movement of the bridge 10 along the guide rails 13 are
orthogonal to the vertical direction of the mast 12B, thereby providing
three-dimensional movement of the end effector 21. Rotational movements
of the end effector 21 can provide at least two additional degrees of
freedom. In this embodiment, the guide rails 13, trucks 14, mast 12B,
bridge 10 and end effector 21 thereby provide five degrees of positioning
movement. It should be understood that this is but one form of a
positioning or robotic device to provide such movement wherein other
robotic devices can be used to achieve desired positioning of an aligning
fixture, which in this exemplary embodiment can be selectively coupled to
the end effector 21 or a support therefor.

[0043]In the embodiment illustrated in FIG. 2, the, holding assembly 17
typically comprises a plurality of support assemblies 19 (each of which
is configured to engage a portion of a workpiece (not illustrated). In
general, as an aspect of the invention, the holding assembly 17 includes
a plurality of support assemblies 19. Each support assembly 19 includes a
head or end 22 for engaging and supporting a workpiece. In one
embodiment, the head 22 includes a vacuum cup assembly 23, although it
should be understood other heads having other devices (such as but not
limited to protrusions, apertures, clamps and/or magnets) to engage and
hold the workpiece can be used if desired.

[0044]Referring to FIG. 3, the end of the support assembly 19 engageable
with the workpiece is connected to a rod 24 that is movable, for example,
slidable, with respect to a brake assembly 26 that selectively engages
the rod 24 and holds it in a fixed position when desired. The aligning
assembly or fixture 18 is selectively coupled to the end effector 21 (or
the support therefor) and engages or is selectively coupled to the head
or end 22 of the support assembly 19. One or more elements of the
positioning system provided, herein by example system 11, such as but not
limited to the end effector 21, if present, the assembly on the end of
the mast 12A used to position the end effector 21, the mast 12A and/or
any other part of the positioning system 11, are used to manipulate
(pull, push, lift, pivot, etc.) head 22 of the support assembly 19 in
multiple degrees of freedom (commonly 2 or more degrees of freedom
depending on the degrees of freedom provided by the support assembly) to
obtain the desired position of the head 22, typically 3-dimensional
space, such that the head 22 is in proper position to receive a portion
of the workpiece. Although in this embodiment,

[0045]The support assembly 19 and portions thereof are illustrated in
FIGS. 3-6. Referring first to FIG. 3, head 22 includes a device 40 for
engaging the workpiece herein exemplified as the vacuum cup assembly 23
comprising a support block 41 and a flexible cup member 42 surrounding
the support block 41. The cup member 42 includes a rim 44 that can
sealingly engage the workpiece to hold the head 22 in a fixed position
thereon.

[0046]A pivoting assembly 50 supports the vacuum cup assembly 23 and
allows it to be pivoted to a selected position respect to a longitudinal
axis of the rod 24. The pivoting assembly 50 includes a guided member 52
guided with respect to a fixed support 54. In particular, the guided
member 52 and the support 54 include complimentary engaging surfaces so
as to allow the guided member 52 to pivot or rotate about a fixed axis in
an accurate manner. In the embodiment illustrated, the support 54
includes one or more support brackets 56. The guided member 52 is
disposed between the support brackets 56 and is movably guided thereon
with a guide assembly 53. In the embodiment illustrated, the guide
assembly 53 includes a channel 58 on each support bracket 56 adapted to
receive arcuate projection 60 formed on opposite sides of the guided
member 52. As appreciated by those skilled in that art, other guide
assemblies having cooperating guide components can be used, such as but
not limited to where the guided member 52 includes a guide channel and
the support member 54 (such as support brackets 56) include projection(s)
configured to be guided in the guide channel.

[0047]In the embodiment illustrated, the guided member 52 is disposed
between the brackets 56 such that the projections 60 engage each
respective channel 58. Fasteners 57 and securing plates 59 secure the
brackets 56 to the guided member 52 allowing sliding movement thereof
with suitable friction such that when the desired position of the guided
member relative to the brackets 56 is obtained the position will be
maintained so as to hold the workpiece. In the embodiment illustrated,
the securing plates 59 are configured to fit within recesses 61 provided
in each respective bracket 56. Each of the brackets 56 in turn are
mounted to a support plate 62 with fasteners 64.

[0048]Support block 41, which typically will directly engage the
workpiece, is secured to the guided member 52 with fasteners such as
fasteners 65 extending through suitable apertures in the guided member 52
and the cup member 42. A fitting 66 can be provided and is connected to
suitable passageways in order to draw a vacuum in the cup member 42 when
desired.

[0049]Rather than having the aligning fixture apply force directly upon
the support block 41 and/or the vacuum cup 42 to obtain the desired
position thereof, the guided member 52 is arranged with surfaces that can
be engaged. In the embodiment illustrated, a plate member 68 is disposed
about the vacuum cup assembly 23 and secured to the guided member 52 with
fasteners 70 to provide surfaces that can be engaged by aligning fixture
18. In one embodiment as illustrated, plate member 68 and/or the guided
member 52 can include aligning surfaces 74 herein illustrated as recesses
that cause the aligning fixture 18 to engage or grip the plate member 68
in a known, predetermined manner so that in turn the position the head 22
can be adjusted in a selected position when desired. As appreciated by
those skilled in the art, other forms of aligning surfaces formed or
provided on, for example, protrusions or apertures can be used.

[0050]The aligning fixture 18 has complementary members adapted to engage
and release the aligning surfaces 74 when desired. In one embodiment, the
aligning fixture 18 includes movable member(s) or fingers that can grip
and release the head 22 using the aligning surfaces as they are formed on
the head 22. In many applications but maybe not all applications, it is
important that the aligning fixture 18 grip the head 22 in a known manner
so that accurate and repeatable coupling exists between the aligning
fixture 18 and the head 22. In this manner, the aligning fixture 18, when
moved, will also move the head 22 to the desired position in order to
support a portion of the workpiece.

[0051]A particularly advantageous feature of the pivoting assembly 50 is
that it is configured so that pivoting motion of the guided member 52
results in the support block 41 (or other element engaging the workpiece)
pivoting about an axis 41B (FIG. 3) that coincides with the point of
contact with the workpiece. In other words, the point of contact lies on
or intersects with the axis about which the pivoting assembly 50 pivots.
In the embodiment illustrated, the axis would lie on the contact surface
41A of the support block 41. Specifically, the guided member 52 and
guiding assembly 53 are configured so as to place the axis 41B about
which pivoting occurs on (coincides with) the contact surface 41A of the
support block 41 (i.e. the point of contact with the workpiece). In the
embodiment illustrated, the radius of the projection 60 and/or the
channel 58 coincide with the axis 41B at this position. This feature is
particular advantageous because no compensating adjustments or
calculations need to be made and performed by component(s) of the
positioning system 11 in order for the system 11 to adjust the head 22 so
that it is in a proper position to support the workpiece.

[0052]In order to position head 22 in a reference position about a
longitudinal axis 24A extending through rod 24, a twisting mechanism 80
(FIGS. 3 and 5) is provided to rotate head 22 and rod 24 about the
longitudinal axis 24A of rod 24. Twisting mechanism 80 includes
complimentary engaging surfaces 82 and 84. Engaging surface 82 is fixedly
secured to head 22 or rod 24, while engaging surface 84 is fixedly
secured to brake 26, which is held in a fixed stationary position. Of
course, any other element held in a fixed stationary position could also
be used instead of brake 26. In the embodiment illustrated, twisting
mechanism 80 operates to rotate or twist head 22 and rod 24 as head 22
and rod 24 are lowered toward brake 26. Engaging surfaces 82 and 84
engage each other as the rod 24 and head 22 are lowered and slip by each
other to cause twisting of the rod 24 toward the selected position where
the surfaces 82 and 84 come to rest in a reference position. Although
various forms of complimentary engaging surfaces 82 and 84 can be used,
in a particular advantageous embodiment, the complimentary engaging
surface 82 includes a portion 82A that converges to a narrower end or
point that upon engagement with any portion of the engaging surface 84
causes the portion 82A to twist rod 24 about longitudinal axis 24A and
slide downwardly so that portion 82A comes into engagement with a
complimentary portion 84A formed on engaging surface 84.

[0053]Referring also to FIG. 5, in a further embodiment, engaging surfaces
82 and 84 are each formed on corresponding collars 82B and 84B that
encircle rod 24. Engaging surfaces 82 and 84 are generally at least
proximate to if not residing in a plane 88. Plane 88 is oblique to rod 24
and longitudinal axis 24A. As illustrated, rod 24 extends through plane
88. Stated another way, different portions of the engaging surface 82 are
located at different axial positions along the longitudinal axis 24A.

[0054]Various forms of brakes can be used to hold rod 24 along its
longitudinal axis in a desired position. An advantageous form of brake 26
is illustrated in FIG. 6. In this embodiment, brake 26 includes an
expandable member 100 herein in the form of an expandable tubular body
encircling the rod 24. When pressurized by a suitable fluid such as air,
the expandable body 100 expands inwardly, reducing the diameter of its
center aperture, to create a force that is applied to an outer surface of
the rod 24. Although the inner surfaces of expandable body 100 could be
configured to engage rod 24 directly, in a further embodiment, a gripping
sleeve 102 is interposed between the outer surface of the rod 24 and
inner surfaces of expandable body 100. The gripping sleeve 102
substantially encircles the rod 24 but includes a longitudinal slot 104
so as to allow surfaces defining slot 104 to compress toward each other
(decreasing the diameter of sleeve 102) due to forces created by the
expandable body 100.

[0055]In yet a further embodiment, gripping sleeve 102 can include flanges
106 at opposite ends thereof, or otherwise be configured so as to engage
inner surfaces of support blocks 108. In other words, when assembled,
gripping sleeve 102 can not move longitudinally along axis 24A between
support blocks 108, but rather, is held in a fixed position
longitudinally. Thus, when brake 26 is operated, the brake 26 holds rod
24 in a fixed longitudinal position as a rigid connection is formed
between blocks 108 (where one or both are attached to a suitable
stationary frame member) and the gripping sleeve 102, that in, turn grips
rod 24. It should be noted expandable body 100 includes a mounting
flange, herein annular ring 110, that is trapped between and engages end
surfaces 112 locks 108 which face each other.

[0056]Suitable bearing assemblies are provided in brake 26 to allow
sliding movement of rod 24 relative to brake 26, when brake 26 is not
actuated. In the embodiment illustrated, a bearing assembly 114 is
provided for each of the blocks 108. Each of the bearing assemblies 114,
which can comprise individual bearing elements, or be formed from a
suitable bearing compound well known in the art, is received in counter
bores 116 provided in each of the blocks 108. Fasteners 118 join support
blocks 108 together.

[0057]A support assembly 200 having a workpiece holding head 202 that can
move in at least two degrees of freedom relative to a support rod 204 is
illustrated in the FIGS. 7-8. Head 202 is similar to end or head 22
described above and similar components of head 202 are identified with
same reference numbers as used above with respect to head 22. In this
embodiment, support brackets 56 are mounted to a movable base 206 that is
coupled to support rod 204 to move relative thereto in at least two
dimensions via a coupling assembly 207. The coupling assembly 207
includes at least one sliding member coupled to the movable base 206 with
an optional link assembly. In the embodiment illustrated, an upper brake
assembly 208A and a lower brake assembly 208B slidable on support rod 204
and a link assembly 210. In addition to pivotable movement of head 202 in
a manner similar to head 22 described above, head 202 is movable at least
in a two-dimensional space relative to support rod 204. In particular,
head 202 is movable up and down in a direction parallel to a longitudinal
axis 204A of rod 204 as well as in a direction orthogonal to the
longitudinal axis 204A of rod 204 along a substantial length of rod 204.
Stated another way, the two-dimensional space is defined by movement of
the head 202 along an axis parallel to the axis of support rod 204 and/or
in a direction inwardly or outwardly with respect to the support rod 204.
However, the head 202 can move in a three-dimensional space due to
rotation of the head 202, link assembly 210 and brake assemblies about
the axis 204A of the support rod 204, if desired. Positioning of head
202, and in particular movable base 206, in a two or three-dimensional
space is obtained by selective positioning of the upper brake 208a and
the lower brake 208b along and/or about the support rod 204. In one
embodiment though, an alignment rod 214 is provided and is disposed
parallel to support rod 204 in order to inhibit movement of head 202 and
moveable base 206 about longitudinal axis 204A. In the exemplary
embodiment, only lower brake 208B is slidable along support rod 204 and
alignment rod 214, although either or both can be configured as such.

[0058]Link assembly 210 includes an upper link arm 220 joining the
moveable base 206 to the upper brake 208A and two spaced-apart links
comprising a control arm 222 and a swing arm 224 both of which pivotably
join the moveable base 206 to the lower brake 208B. The link assembly 210
hereby maintains a fixed orientation of movable base 206 with respect to
support rod 204, but allows up and down and inward and outward movement
of the movable base 206 as described above. As appreciated by those
skilled in the art, link assembly 210 can take numerous forms, wherein
the present embodiment should not be considered limiting.

[0059]In the embodiment illustrated, both upper brake 208A and lower brake
208B are constructed in a manner similar to brake 26 described above
where like components have been identified with similar reference
numbers. The upper brake 208A is illustrated in FIG. 9 while the lower
brake 208B is illustrated in FIG. 10. This lower brake 208B also slides
along alignment rod 214. Brake 208B includes an additional bearing sleeve
230. The brakes 208A and 208B can be operated simultaneously or
separately as desired.

[0060]Referring back to the embodiment of FIGS. 7 and 8, support rod 204
and alignment rod 214 extend upwardly from a base 240. In the exemplary
embodiment, base 240 includes a plurality of plate members herein a lower
plate member 242, an upper plate member 244 and two vertically oriented
plate members 246 and 248. An upstanding frame member 250 provides
support for the support rod 204 and alignment rod 214 on ends opposite
the base 240. A first transverse plate 252 extends between panels of
frame support 250 to provide rigidity. A second transverse plate 254
includes an aperture 256 to which a ball element 258 can be placed that
is used to engage and secure an end of the support rod 204 remote from
the base 240.

[0061]As an advantageous feature, the head 202, and in particular, the
moveable base 206 can be selectively returned to a reference position. In
the embodiment illustrated, this occurs when the upper brake 208A and the
lower brake 208A are brought together at an end at of the support rod
204. In one embodiment, this can occur at the end proximate the base 240
by disengaging each of the brakes 208A and 208B and allowing them to
slide along and settle at the bottom of the support rod 204 proximate
base 240. However, in an alternative embodiment, the upper brake 208A and
the lower brake 208B can be brought to the top of the support rod 204
remote from the base 240 where upon the brakes 208A and 208B are engaged
or operated so as to maintain their position at the top of the support
rod 204. In this alternative embodiment, a lifting bracket 270 can be
provided and used to selectively lift lower brake 208B, which in turn,
will engage and lift upper brake 208A as needed. Of course, engagement of
the lower brake 208B with the upper brake 208A is not required if the
lower brake 208A and the upper brake 208A otherwise obtain reference
positions relative to each other, for instance, again using lifting
bracket 270. For example, the link assembly 210 could be of a
construction that inhibits contact between the lower brake 208B and the
upper brake 208A, but nevertheless, the positions of the lower brake 208B
and the upper brake 208A are known and repeatable using, for instance,
lifting bracket 270. Likewise, an intermediate spacer, for example, also
secured to and possibly slidable on support rod 204 can be present that
would inhibit contact between the lower brake 208B and the upper brake
208A. The spacer could be used to help define one or both of the
reference, repeatable positions of the lower brake 208B and the upper
brake 208A, when for example lifting bracket 270 is used, or the spacer
would not otherwise contribute to unrepeatability of the lower brake 208B
and the upper brake 208A from obtaining such reference positions.

[0062]In the embodiment illustrated, lifting bracket 270 includes a plate
member 272 having an aperture 274 into which a lifting hook (now shown)
can extend therethrough when necessary to lift bracket 270. Elongated
rods 276 extend downwardly from plate 272. The rods 276 slidably extend
through apertures in brake 208B. Ends of the rods 276 remote from the
plate 272 have enlarged heads that are larger than the apertures in brake
208B. In this manner, when lifting bracket 270 is lifted upwardly
enlarged heads on rods 276 will engage and lift the lower brake 208B.
Subsequently, when the brakes 208A and 208B disposed at the end of the
support rod 204 remote from the base 240 are operated so as to maintain a
fixed position, the lifting bracket 270 can be lowered since the rods 276
slide through the apertures provided in the lower brake 208B.

[0063]The aligning fixture or assembly 18, which is of exemplary form, is
illustrated in FIGS. 11-13. Generally, the aligning fixture 18 includes a
frame 300, an interface coupling 302 and a gripper assembly 304. The
interface coupling 302 selectively couples to end effector 21 and
includes fluid ports and/or electrical connections to operate the
aligning fixture 18. The gripper assembly 304 includes gripping fingers
or projections 306 one or both of which are movable by an actuator(s)
(schematically illustrated at 308, where dashed lines extending from the
actuator 308 represent rods, levers, etc that connect the actuator(s) to
the gripping finger(s)s 306) to grasp the heads 22 or 202 so as to allow
reorientation thereof. (As appreciated by those skilled in the art such
an actuator assembly can take a wide variety of forms, the structure of
which is not pertinent to the inventive aspect herein described.) As
discussed above, plate 68 can be provided with aligning recesses 74,
which the gripping fingers 306 can engage in order to provide a
predetermined position between the head 22 or 202 and the aligning
fixture 18.

[0064]Also provided on gripper assembly 304 is registration plate 310,
which emulates the position of a portion of a workpiece the support
assembly 19,200 will support. If the support assembly 19,200 is equipped
with a vacuum cup 42, a vacuum can be drawn with engagement of the vacuum
cup 42 upon registration plate 310. A pressure sensor (not shown) fluidly
coupled to a port in the registration plate 310 can be provided to sense
the vacuum and ensure a proper seal is obtainable. If desired, the vacuum
can pull the head 22/202 until the block 41 contacts the registration
plate 310. If a desired vacuum has been obtained this can indicate proper
operation and position has been obtained. When desired, atmospheric air
can be allowed to enter the vacuum formed in the cup 42, thereby
releasing the vacuum. The support assembly 19,200 can include a valve to
allow air into cup 42. At this time or earlier, the brake 26, 208A, 208B
of the support assembly 19,200 can be operated to lock the position of
the head 22, 200.

[0065]In a further embodiment, aligning fixture 18 can include an actuator
320 such as a fluid operated piston/cylinder or screw operated actuator
that is connected to the gripper assembly 306 and frame 300 to allow the
gripper assembly 306 to move relative to frame 300. In the embodiment
illustrated, aligning rods 322 move with the gripper assembly 306
relative to support bearings 324 to maintain alignment of the gripper
assembly 306 when extended or retracted. Suitable cabling 326 is provided
between the gripper assembly 306 and the frame to maintain electrical
and/or fluid connections.

[0066]The aligning fixture 18 is mounted to the end effector 21, or
support therefore, and is used to align each head 22 and/or head 202 of
each support assembly 19, 200 for the workpiece to be supported by the
holding assembly 17. Generally, the desired position for each head 22,
202 of each corresponding support assembly is provided to a controller
160 in FIG. 2. The controller 160 provides suitable control signals
(represented by arrow 162) to operate motors controlling the placement of
the bridge 10 on the guide rails 13, the mast 12B on the bridge 10, the
extension of the mast 12B and the orientation of the end effector 21 in
order to obtain desired positions of the aligning fixture 18. The
controller 160 also operates (e.g. brakes, vacuum, etc.) each of the
support assemblies 19, 200 herein represented by arrow 164.

[0067]In one embodiment, the positions of each head 22, 202, or
specifically, the support blocks 41 thereof, can be ascertained manually
by placing the workpiece on the holding assembly 17 and individually
adjusting each of the support assemblies 19, 200 until the proper
position of each remote end 40 has been obtained at which point
measurements can be obtained and stored for future use. In another
embodiment, a representation of the holding assembly 17 is stored in
memory of a computer represented by block 168 thereby comprising an
analytical model. A model of the workpiece is combined with the model of
the holding assembly 17 so as to calculate the orientation and/or
position of each head 22, 202 of each support assembly 19, 200 that will
be used to support the workpiece. The positional information of each
remote end calculated from the model 168 is then used by the controller
160.

[0068]With the positional information known for each head 22, 202 of each
support assembly 19, 200 and the aligning fixture 18 coupled to the end
effector 21, or support therefor, the controller 160 operates the system
to cause the aligning fixture 18 to engage a selected support assembly
19, 200 and adjust the corresponding head 22, 202 to coincide with the
surface of the workpiece to be placed on the holding assembly 17.

[0069]FIGS. 14-17 are flowcharts illustrating registration of support
assemblies ("SA") on the holding assembly, support assembly programming
for a specific workpiece or part, actual setting of the support
assemblies for the part, and loading the part on the fixture,
respectively. Referring first to FIG. 14, this flowchart illustrates
registration of support assemblies (19 and/or 200, herein "19,200") on
the holding assembly 17, which includes taking measurements of the
support assemblies 19, 200 so as to provide corrections due to minor
positional errors depending on the extension of the support assembly 19,
200. For purpose of explanation and understanding only, assume that a
support assembly 19 or 200 is to be mounted on a holding assembly 17 so
that extension would be vertically such as illustrated in FIGS. 18 and
19. As another aspect of the invention, compensation is provided in
configuring each support assemblies 19, 210 for positioning errors that
can result from differences between the predicted position of the end of
the support assembly 19, 200 and its actual position, and in a further
embodiment, particularly for positioning errors that are dependent upon
selective extension of the corresponding support assembly rod 24, 204.

[0070]Referring to FIG. 20, a portion of a workpiece is illustrated at
400, while extension of the rod of a support assembly is indicated by
line 402. In other words, line 402 represents actual extension of the
rod, while line 404 represents a perfect normal line that the rod
(positions of the head) would have presumed to extend given the location
of the support assembly 19, 200 on the holding assembly 17. There thus
exists positioning errors for one, some or all of the support assemblies
when in use. In FIG. 20, it can be seen that the support assembly 19, 200
would actually support the workpiece at location 406 while it would have
been presumed that it should hold it at predicted location 408. It is
this difference between presumed and actual holding that is compensated
for with the techniques described herein. It should be understood that
the difference between lines 402 and 404 and locations 406 and 408 have
been exaggerated for purposes of illustration and understanding.

[0071]Referring back to FIG. 14, with the holding assembly 17 populated
with support assemblies 19, 200, the positioning system 11 uses a probe
on the end of end effector to ascertain positions of each of the support
assemblies 19, 200 so as to provide compensation for each of the support
assemblies 19, 200. In the embodiment illustrated, steps indicated by
bracket 410 illustrate recording the preselected reference position of
the support assemblies 19, 200 prior to movement to a position to hold
the workpiece. For support assembly 19, this typically corresponds to an
unextended position or "down" (lowermost) position of the head 22 of the
support assembly 19 as provided by way of example in FIG. 14. For support
assembly 200, the preselected reference position can be the lowermost or
the uppermost position of the movable base 206 relative to the rod 204.
(If necessary, it should be noted that each of the heads 22, 202 can be
oriented (i.e. tilted) as necessary to achieve the reference positions.)
These positions (e.g. with respect to a three axis coordinate system) are
recorded, for example by controller 160, in a database 412 on computer
readable medium such as memory, hard disk, etc. Steps indicated by
bracket 414 illustrates reconfiguration of positioning assembly 11 to use
an end effector 21 such as aligning fixture 18 suitable to engage each of
the support assemblies and position each in an "extended" position (i.e.
a position that is remote from the corresponding reference position). By
way of example in FIG. 14, this position is referred to the "up"
position, which would be typical for support assembly 19. For support
assembly 200, the extended position would be remote from reference
position, for example, where the link assembly 210 extends the head 202
outwardly and at generally at an opposite end of the shaft 204.

[0072]Similar to steps 410, steps indicated by bracket 416 record the
extended position of each of the support assemblies which is also stored
in database 412. Using the extended and reference positions of each of
the support assemblies, a vector in three dimensional space can be
ascertained for each support assembly 19, 200 to represent the position
errors associated with each support assembly 19, 200, and stored if
necessary, as indicated by step 420. Generally, ascertaining the
positional errors of each support assembly 19, 200 provides a basis upon
which compensation can be provided for each support assembly 19,200, if
needed, so as to hold the workpiece better (such as but not limited to
providing more accurate support or positioning of the workpiece, more
stability of the workpiece on the holding assembly 17 and/or minimize
stress induced in the workpiece from the holding assembly 17).
Compensation can include positioning the head of the support assembly
based on the ascertained positioning error for that support assembly,
which can also include adjusting the rotation of the head about the
support rod and/or tilt of the head.

[0073]The fixture or holding assembly 17 with the support assemblies 19,
200 is modeled in a CAD environment that allows an operator to see and
adjust in a virtual manner the holding assembly 17 with a suitable
computer as is known in the art. Data 422 indicates that the CAD model of
the holding assembly 17 with support assemblies 19, 200 is updated with
the support assembly vectors at step 420 which take into account errors
due to the actual positions of each of the support assemblies 19,200 when
each is selectively positioned at a holding position to support the
workpiece (i.e. when the support assembly needs to be moved from its
reference position to some extended position to hold/contact the part or
workpiece).

[0074]FIG. 15 illustrates support assembly programming in a CAD or virtual
environment simulated on a computer. Using a CAD model of the part 424
and the updated CAD model 422 of the holding assembly 17, the operator
virtually positions the part in the work envelope of the fixture or
holding assembly 17 as indicated at step 426. Step 428 illustrates
identification of support assemblies 19,200, typically two, that include
a locating element (protrusion or aperture), not shown, for example
extending up from or formed into support block 41 that are used to
register the workpiece on the holding assembly 17.

[0075]At step 430, and using FIG. 20 for illustrative purposes, the
location 406 is ascertained where the outer contour of the workpiece and
the vector 402 representative of an actual support assembly intersect. In
addition, a vector 434 that is normal to the outer surface of the
workpiece at the point of intersection 406 is also ascertained at step
432. The location of intersection 406 and the associated vector 434 is
ascertained for each support assembly and is data that is recorded on
computer readable medium as illustrated at 436. Step 438 represents
processing of data 436 so as to ascertain data 440 indicative of
parameters that can be used by controller 160 for setting each of the
actual support assemblies. As was described above, each support assembly
includes a positioning assembly (e.g. 50) that allows the support block
(e.g. 41) to be tilted to a desired position. The normal vector 434 is
used to calculate the necessary rotation of the support assembly about
the axis of its rod (e.g. 24) and the necessary tilt of the positioning
assembly to properly orient the support assembly to achieve the
intersection point 406. For completeness, step 442 indicates that the
support assemblies can be organized in groups as desired, while output
444 indicates that an image of the workpiece on the fixture can be
created.

[0076]FIG. 16 illustrates set up of the actual holding assembly to receive
the actual part. For this purpose, the controller 160 uses data 440 and
data 412. Step 450 represents a check to see if all the support
assemblies are properly positioned for the workpiece. For example, if the
system is working on a second workpiece that is the same as a first
fixture that it just held, there is no need to perform the steps
illustrated in FIG. 16.

[0077]Assuming that one or more of the support assemblies 19,200 need to
be positioned, each of the support assemblies 19,200 that need
positioning are positioned using, by way of example, the steps indicated
by bracket 454. It should be noted that steps 456 and 458 relate to
obtaining the proper orientation about the axis 24A of the support
assembly rod 24 (herein support assemblies 19) and tilt of the support
block 50 (support assemblies 19 or 200), as mentioned above. For
completeness, FIG. 17 illustrates steps for loading an actual workpiece
on the holding assembly 17 once the support assemblies have been properly
configured.

[0078]The system controller 160 each can be implemented on one or more
digital and/or analog computers. FIG. 21 and the related discussion
provide a brief, general description of a suitable computing environment
in which the system controller 160. Although not required, the system
controller 160 can be implemented at least in part, in the general
context of computer-executable instructions, such as program modules,
being executed by a computer 370. Generally, program modules include
routine programs, objects, components, data structures, etc., which
perform particular tasks or implement particular abstract data types.
Those skilled in the art can implement the description herein as
computer-executable instructions storable on a computer readable medium.
Moreover, those skilled in the art will appreciate that the invention may
be practiced with other computer system configurations, including
multi-processor systems, networked personal computers, mini computers,
main frame computers, and the like. Aspects of the invention may also be
practiced in distributed computing environments where tasks are performed
by remote processing devices that are linked through a communications
network. In a distributed computer environment, program modules may be
located in both local and remote memory storage devices.

[0079]The computer 370 illustrated in FIG. 21 comprises a conventional
computer having a central processing unit (CPU) 372, memory 374 and a
system bus 376, which couples various system components, including memory
374 to the CPU 372. The system bus 376 may be any of several types of bus
structures including a memory bus or a memory controller, a peripheral
bus, and a local bus using any of a variety of bus architectures. The
memory 374 includes read only memory (ROM) and random access memory
(RAM). A basic input/output (BIOS) containing the basic routine that
helps to transfer information between elements within the computer 370,
such as during start-up, is stored in ROM. Storage devices 378, such as a
hard disk, a removable data storage device, an optical disk drive, etc.,
are coupled to the system bus 376 and are used for storage of programs
and data. It should be appreciated by those skilled in the art that other
types of computer readable media that are accessible by a computer, such
as magnetic cassettes, flash memory cards, digital video disks, random
access memories, read only memories, and the like, may also be used as
storage devices. Commonly, programs are loaded into memory 374 from at
least one of the storage devices 378 with or without accompanying data.

[0080]Input devices such as a keyboard 380 and/or pointing device (mouse)
382, or the like, allow the user to provide commands to the computer 370.
A monitor 384 or other type of output device is further connected to the
system bus 376 via a suitable interface and provides feedback to the
user. If the monitor 384 is a touch screen, the pointing device 382 can
be incorporated therewith. The monitor 384 and typically an input
pointing device 382 such as mouse together with corresponding software
drivers form a graphical user interface (GUI) 386 for computer 370.
Interfaces 388 on each of the system controller 60 allow communication
between system controller 160 elements of the positioning system such as
a separate controller used to provide command signals that for drive
elements (motor controllers, servo valves, etc.) of the positioning
system 11 to cause manipulation thereof. Interfaces 88 can also represent
circuitry used to send signals to or receive signals to such
controller(s) or directly to the actuators and/or sensing devices (e.g.
contact sensors to measure the reference positions and remote positions,
pressure sensors, etc.) as mentioned above. Commonly, such circuitry
comprises digital-to-analog (D/A) and analog-to-digital (A/D) converters
as is well known in the art. In another computing environment, the system
controller 160 and each of the various other controllers are each a
single board computer operable on a network bus of another computer, such
as a supervisory computer. The schematic diagram of FIG. 21 is intended
to generally represent these and other suitable computing environments.

[0081]Although the subject matter has been described in a language
specific to structural features and/or methodological acts, it is to be
understood that the subject matter defined in the appended claims is not
necessarily limited to the specific features or acts described above as
has been determined by the courts. Rather, the specific features and acts
described above are disclosed as example forms of implementing the
claims.